The nation's celebrations for the royal wedding and the long bank holiday weekend prompted a splurge in sales of picnic food, bunting, champagne, wine and barbecues.

Waitrose reported a 23% rise in sales in the week to last Saturday, compared with the week following Easter last year. Bunting, union flags, paper plates and cups quickly sold out before Kate and William's big day. The upmarket grocer's royal trifle, created by celebrity chef Heston Blumenthal, also sold out. Meanwhile many customers made their own and sales of trifle sponges were up 370%. Post-party clean-ups prompted soaring sales of bin liners, foil and cling film.

"The weather, the royal wedding and extra bank holiday combined mean that it's been a good weekend for food and DIY retailers," said Sarah Cordey of the British Retail Consortium. "There was a lot of promotional activity."

The unusually hot Easter weekend also provided a big boost, "not just in terms of people eating out but also new seasonal fashion," she added.

The BRC releases its latest retail sales figures next Tuesday.

On the day before the wedding, Waitrose enjoyed its strongest sales on a Thursday outside the Christmas and new year period. This follows a record pre-Easter week, when sales climbed by 10.6% compared with the week before Easter last year.

"The celebratory mood that swept the nation drove another week of strong sales, with the mid-week days showing particularly impressive uplifts as people got ready for royal wedding parties and the long weekend," said Waitrose's managing director Mark Price. "We've seen a wave of entertaining across the country, which would only be rivalled by the Christmas and new year period."